Enhanced high temperature dielectric polarization of barium titanate/magnesium aluminum spinel composites and their potential in microwave absorption

Antioxidant materials with high permittivity are highly desirable for thin, microwave-absorbing materials at high temperature (MAMHT) due to their great impedance matching. In this work, composite ceramics composed of BaTiO₃ and MgAl₂O₄ (BTMAS) synthesized by a traditional solid-state sintering method have been studied for their high temperature microwave dielectric properties. When the temperature rose between 473 K–573 K, the real part of permittivity (ε’) of BTMAS increased significantly relative to room temperature. As the temperature increased further to 873 K, ε’ gradually fell. Based on the collection of permittivities obtained by the inverse resolution of specific reflectivity, BT36 (36 mol % BaTiO₃) was suitable for 1.1 mm thick microwave-absorbing materials from 300 K – 873 K. The envisaged material had an absorption bandwidth of 2 GHz (RL<-5 dB) which could move between microwave X-band as the temperature changed. Therefore, there is great potential for BTMAS in reducing the thickness of MAMHT.